20k for a Glock (or a lot of other modern pistols) is nowhere near the end of the line. The gas cutting/erosion shown in the picture is not normal wear, even for a 20k gun. It's not like replacing springs, connectors, locking blocks, pins or mags. It's the slide. Sure it's a $500 tool, but if you can increase it's service life by using the proper primers, why wouldn't you? You obviously have your mind made up about this, so just use them & don't worry about what anyone else thinks.